The method for welding profiled elements made of a plastic material, in particular PVC, comprises the steps of: preparing two profiled elements (3) made of a plastic material, arranged with respective zones to be welded (4) facing one another; heating the zones to be welded (4); before the heating step, the step of making a groove (19) in correspondence to a peripheral edge of each of the zones to be welded (4); coupling the zones to be welded (4) to one another, by pressing the profiled elements (3) against one another to keep the zones to be welded (4) in reciprocal contact, the step of coupling the zones to be welded (4) defining a sub-step of melting the zones to be welded (4) into one another to define a welding bead and comprising the sub-steps of: arranging pressing means (27, 28) in correspondence to the grooves (19) to define, in collaboration with the grooves (19), a containing compartment (19a) of the welding bead, the pressing means (27, 28) comprising: - a first work surface (62) having a protruding portion (63); and a second work surface (64) of final finishing; and displacing the pressing means (27, 28) alternately between: an idle position moved away from the profiled elements (3); a first work position wherein the first work surface (62) is abutted on the grooves (19) with the protruding portion (63) located inside the containing compartment (19a) to deviate the welding bead towards the side walls (61) of the containing compartment (19a); and a second work position wherein the second work surface (64) is abutted on the grooves (19) so as to obtain a finished welding bead.